The present invention relates to a semiconductor integrated circuit device having a plurality of integrated circuit chips mounted on a circuit board and, more particularly, to a semiconductor integrated circuit device which is equipped with a cooling system serving to remove heat generated by integrated circuit chips having high power dissipation.
In an electronic computer and the like, integrated circuit chips having high power dissipation are mounted on a circuit board at high density in order to perform the circuit operation at high speed. The power dissipation of these integrated circuit chips reaches thousands W (watts) on the circuit board so that, in order to assure the circuit operation, a powerful and compact cooling system becomes indispensable. Conventional techniques concerning the cooling of the semiconductor integrated circuit device having such integrated circuit chips mounted on the circuit board include the one disclosed in U.S. Pat. No. 4,558,395, for example. According to the technique disclosed in the U.S. Pat. No. 4,558,395, a cooling member is made to contact with each integrated circuit chip and coolant is supplied to the cooling member, thereby effecting the cooling. Flexible pipes are used as means for supplying coolant so as to absorb or compensate unevenness in height of the integrated circuit chips caused by the warp of the circuit board or the like, so that the integrated circuit chips and the cooling members are kept in good contact with each other. According to this cooling system, in case that water is used as the coolant, it is possible to remove the power dissipation of 100 W per 1 cm.sup.2, for example.
However, in such cooling system, all the connections between a plurality of pipes and the cooling members must be so joined as to prevent leakage of the coolant. Further, the load caused by the elasticity of the pipe and the pressure of the coolant is applied to each integrated circuit chip, resulting in the possibility that the reliability of connecting terminals serving to connect the integrated circuit chips to the circuit board is deteriorated. In addition, if the pipes and the cooling members are made of metallic materials of different kinds respectively, the coolant comes in contact with the galvanic contacts to bring about the reduction of corrosive life.
To cope with such problem, there has been known a technique that integrated circuit chips are mounted on a rigid circuit board through flexible members and that the whole back (upper surface) of every integrated circuit chip is forced to bear against a cooling system having a surface of very high flatness by the pressing force applied from a side of the rigid circuit board. According to this technique, difference in gap between the respective integrated circuit chips and the cooling system is absorbed or compensated by the flexible members so that cooling of the integrated circuit chips can be effected by one cooling system with simple construction. Such technique is disclosed in Japanese Patent Unexamined Publication No. 59-50552(A), for example.
However, according to this cooling system, if the pressing, force applied from the side of the circuit board is not adjusted sufficiently, it is impossible to stick all the integrated circuit chips to the cooling system with reliability. Namely, since the circuit board is a rigid body there is a possibility that all the integrated circuit chips cannot be forced to bear against the cooling system correctly due to the warp of the circuit board or the like. Further, the integrated circuit chips are applied with pressing load by the flexible members at all times. Particularly when lead wires are used as the flexible members, there is caused contact failure due to deformation of the lead wire, failure in the bearing of the chip against the cooling system due to deterioration of the flexibility of the lead wire and the like. Moreover, even in case of replacing the defective cooling system, every integrated circuit chip needs to be detached from and attached to as well as forced to bear against the cooling system, resulting in a heavy burden being placed on the engineer.